/*
  ==============================================================================

   This file is part of the JUCE library - "Jules' Utility Class Extensions"
   Copyright 2004-11 by Raw Material Software Ltd.

  ------------------------------------------------------------------------------

   JUCE can be redistributed and/or modified under the terms of the GNU General
   Public License (Version 2), as published by the Free Software Foundation.
   A copy of the license is included in the JUCE distribution, or can be found
   online at www.gnu.org/licenses.

   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

  ------------------------------------------------------------------------------

   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.rawmaterialsoftware.com/juce for more information.

  ==============================================================================
*/

#ifndef __JUCE_IMAGECONVOLUTIONKERNEL_JUCEHEADER__
#define __JUCE_IMAGECONVOLUTIONKERNEL_JUCEHEADER__

#include "juce_Image.h"


//==============================================================================
/**
    Represents a filter kernel to use in convoluting an image.

    @see Image::applyConvolution
*/
class JUCE_API  ImageConvolutionKernel
{
public:
    //==============================================================================
    /** Creates an empty convulution kernel.

        @param size     the length of each dimension of the kernel, so e.g. if the size
                        is 5, it will create a 5x5 kernel
    */
    ImageConvolutionKernel (int size);

    /** Destructor. */
    ~ImageConvolutionKernel();

    //==============================================================================
    /** Resets all values in the kernel to zero. */
    void clear();

    /** Returns one of the kernel values. */
    float getKernelValue (int x, int y) const noexcept;

    /** Sets the value of a specific cell in the kernel.

        The x and y parameters must be in the range 0 < x < getKernelSize().

        @see setOverallSum
    */
    void setKernelValue (int x, int y, float value) noexcept;

    /** Rescales all values in the kernel to make the total add up to a fixed value.

        This will multiply all values in the kernel by (desiredTotalSum / currentTotalSum).
    */
    void setOverallSum (float desiredTotalSum);

    /** Multiplies all values in the kernel by a value. */
    void rescaleAllValues (float multiplier);

    /** Intialises the kernel for a gaussian blur.

        @param blurRadius   this may be larger or smaller than the kernel's actual
                            size but this will obviously be wasteful or clip at the
                            edges. Ideally the kernel should be just larger than
                            (blurRadius * 2).
    */
    void createGaussianBlur (float blurRadius);

    //==============================================================================
    /** Returns the size of the kernel.

        E.g. if it's a 3x3 kernel, this returns 3.
    */
    int getKernelSize() const               { return size; }

    //==============================================================================
    /** Applies the kernel to an image.

        @param destImage        the image that will receive the resultant convoluted pixels.
        @param sourceImage      the source image to read from - this can be the same image as
                                the destination, but if different, it must be exactly the same
                                size and format.
        @param destinationArea  the region of the image to apply the filter to
    */
    void applyToImage (Image& destImage,
                       const Image& sourceImage,
                       const Rectangle<int>& destinationArea) const;

private:
    //==============================================================================
    HeapBlock <float> values;
    const int size;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ImageConvolutionKernel)
};


#endif   // __JUCE_IMAGECONVOLUTIONKERNEL_JUCEHEADER__
